Sofa beds generally include a support frame having a seating or base portion, a back rest portion and arm rest portions. Unlike standard sofas, the seating portion of a sofa bed includes a storage compartment which is adapted to receive an articulated bed frame when the bed frame is in a folded configuration. The bed frame, when located in the storage compartment, provides a support surface for supporting suitable cushions for completing the seating portion of the sofa.
The bed frame is movable from the storage compartment to a deployed position in which it can be unfolded to form an extended surface for supporting a mattress and other bedding material. For this purpose, the bed frame includes retractable legs which move to a supporting position as the bed frame is being unfolded.
In many sofa bed designs, the bed frame is connected to the support frame by means of a plurality of links which guide the bed frame between the storage compartment and the deployed position. A more recent design includes a roller and track arrangement in which rollers on the bed frame are guided in tracks, or channels, formed in the side panels of the seating portion. This design is attractive because it is much less complicated and generally less expensive than designs employing link-guided bed frames. Moreover, assembly of the bed frame to the support frame is easier because the bed frame is usually connected to the support frame only by the rollers. In link-guided designs there are a number of link members connected between the support frame and the bed frame. Since the link members are normally fastened by rivets, the bed frame is essentially permanently connected to the support frame. This design requires complete assembly of the sofa bed by the manufacturer and makes subsequent disassembly for moving or shipping difficult, if not impossible.
Even with sofa bed designs utilizing a roller and track arrangement for supporting the bed frame, the rollers are mounted in a fashion to make assembly and disassembly difficult and inconvenient at best.